Old-growth, disturbance, and legacies: Fraser Experimental Forest

Bark beetle outbreaks are naturally occurring disturbances throughout upper-montane and subalpine forests in the Rocky Mountains, yet few long-term datasets exist to track forest trajectories pre-, during-, and post-outbreak, and how these outbreaks drive structure and function across spatial scales. Further, little is known about how the legacy of past thinning treatments may influence resistance or resilience to beetle outbreaks and potential for interactions with other disturbances such as fire. Building on permanent plots that were established in the late 1930s at Fraser Experimental Forest in Colorado, we are conducting stem mapping in four replicate 2-ha plots, re-surveying tree mortality, survival, growth, and reproduction, and measuring fuel profiles across a range of disturbance X treatment interactions. We are asking the following questions:

1) How do insect outbreaks affect the spatial pattern of dead and live trees within a stand, and what do these patterns mean for old-growth forest structure?